6.9 earthquake jars Northern California

U-T News Minute

A magnitude 6.9 earthquake broke beneath the seafloor west of Eureka late Sunday night, jarring much of Northern California and parts of southern Oregon, the U.S. Geological Survey says.

The quake erupted at 10:18 p.m., 50 miles from shore, 4.3 miles below the bottom of the ocean's surface, in a region that consistently produces moderate-to-large quakes. It generated shaking that was felt to the south, in San Francisco, and to the northeast, in such places as Medford and Roseburg, Oregon. There also were a few reports of shaking in Portland.

It appears that the temblor broke along the Cascadia subduction zone, which USGS defines online as "a megathrust that forms the collisional plate boundary between the subducting Explorer, Juan de Fuca, and Gorda Plates and the overriding North America Plate, and it extends 1,200 km from offshore northern California to southern British Columbia."